This invention relates generally to methods and apparatus for controlled power generation, and more particularly to methods and apparatus for controlled fuel cell/turbine hybrid power generation
At least one known power system integrates a solid oxide fuel cell (SOFC) generator, which can comprise a single cell or a stack of cells, an unreacted fuel combustor that can be integrated into the SOFC generator or provided as a stand-alone device, and a turbine generator. Such pressurized SOFC/turbine hybrid power generation systems provide high electrical efficiency combined with low emissions. The turbine, which can be a micro-turbine (MT) or gas turbine (GT), serves both to pressurize and provide air to the SOFC generator while the SOFC generator provides heat energy to operate the MT/GT generator. The power output of the plant comprising the combination of the SOFC generator and the MT/GT generator is the combined sum of the SOFC and MT/GT generator electrical outputs.
The SOFC and the MT/GT generators are highly coupled thermally and operationally. Although several strategies for controlling the heat balance of fuel cells and fuel cell generators are known, this coupling has made it difficult to apply these strategies in SOFC/turbine hybrid power generation systems. Further complicating the control of these power generation systems is the fact that the outputs of the generators must also be shared in a way that allows the following of a demanded load. These control requirements must be met at all times and must respond to outside disturbances and local transients.